Wilms' Tumor (WT) is a pediatric malignancy of the kidney which is associated with specific deletions of chromosome 11. The gene which is deleted or mutated on chromosome 11 encodes a DNA binding protein with characteristics of a transcription factor. We have isolated the recognition sequence for DNA binding by this protein and have shown that a mutation identified in a patient with WT abolishes DNA binding activity of the protein. These results form the basis for a simple biochemical assay for the function of a putative tumor suppressor gene involved in the genesis of WT. This proposal will 1) Analyze the structure of the WT gene in human WT tissue samples using a combination of Southern blotting, RNA- PCR and Single Strand Conformation Polymorphism (SSCP) techniques, 2) Analyze the DNA binding activity of the WT protein in these tumors using a combination of gel retardation assays, DNA affinity precipitation (DNAP) and Southwestern blotting techniques, and 3) Establish a new functional assay for the WT protein based on its transcriptional regulation potential in transfected mammalian cell lines. These studies may provide new molecular diagnostic probes to investigate the role of WT gene in different subsets of Wilms' tumors.